Buffer circuits are widely used in many digital systems, and generally provide impedance matching and edge setting functions between an input signal and other circuitry, for example, other circuitry associated with an integrated circuit (IC). In digital mixed signal systems, the input buffer may include one or more switching stages that switch in response to an input signal. While the threshold current that is actually required to switch states in the buffer may be relatively low, impedances in the input buffer can cause a large, sustained current draw when communication between the IC and other circuitry occurs. For example, if the input buffer is powered by a voltage that is greater than the voltage of the input signal, the buffer circuit may draw a large threshold current when switching between states, as well as a continuous current draw while the input is asserted high. The presence of a large threshold current in the buffer can unnecessarily increase the overall power draw of the IC, which, in turn, may limit battery life and create thermal management issues. Conventional approaches for lowering the threshold current include current limiting the buffer, or part thereof, using large resistors and/or large area transistors. However, these approaches require an increase in IC die area to implement, and may adversely (and unpredictably) impact the bandwidth of the buffer and/or the circuitry of the IC.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art.